Centrifuge construction



Nov. 3, 1959 o. w. JOHNSON 2,911,140

CENTRIFUGE CONSTRUCTION Filed Feb. 20, 1956 2 Sheets-Sheet 1 N m N N1 (3 Q 0 "B \l 43 Q Q L Q Q Q &

III I o L o A k) w o o m 0 O INVENTOR. "I Oscar Johnson ATTORNEYS Nov. 3, 1959 o. w. JOHNSON 2,911,140

CENTRIFUGE CONSTRUCTION Filed Feb. 20, 1956 2 Sheets-Sheet 2' 3/ t /0 29 F'JLIE E.-

' IN VEN TOR. Oscar 14 Johnson ATTORNE' VS Uniwd Sm 2,911,140 n V v I CENTRIFUGECONSTRUCITQN Oscar WaJohnson, Houston, Tex assignor, by niesne assignments, to Don-Oliver Incorporated,- Stamford, Conn a corporation of Delaware 7 Application February 20, 1956, Serial No. 566,464 40mins. c1. 'as3--z This invention relates generally to centrifuge machines of the type adapted for the continuous separation and discharge of solid components from a feed material.

Commercial centrifuges are available which are supplied with feed material continuously, as distinguished subject to -troublesome clogging of the underflownozzles. Clogging reduces operating capacity, and makes it necessary to shut down the machine for servicing. Troublesome clogging may be experienced even though screening orsizing methods are used on the feed material. With certain types of feeds clogging'may be caused by. build up of solid material within the centrifuge chamber, with occasional sloughing on of built up fragments. .In other instances clogging may be experienced immediately after the machine is placed in operation following a shutdown period, and may be due to a build up of deposits occurring-during shutdown, which slough off when the machine is started in operation.

In my copending application Serial No. 544,173, filed December 20, 1955, there is disclosed a centrifuge of the continuous type having a screen positioned within the rotor in such a fashion that centrifugally separated underflow material must pass through the same, before discharging through the underflownozzles. The particular construction disclosed in said copending application employs a continuous band of foraminous or screen material, which extends about the main separating chamber, and is interposed between the separating chamber and regions in the periphery of the rotor that communicate with the underflow nozzles. g r n 1 It is an object of the present-invention to provide another type of screen construction which will perform the functions of the screen disclosed in said copending application, and which will afford certain advantages, including ease of servicing.

Another object of the invention is to provide a centrifuge of the above character having screens that are incorporated in conjunction with the nozzle assemblies, and which can be removed from the exterior of the machine, together with the nozzles.

Additional objects and features of the present invention will appear from the following description in which the preferred embodiment has been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure 1 is a side velevational view in one-half section I 2,911,140 Patented Nov. 3, 1959 illustrating a centrifuge incorporating the present invention.--

Figure 2 isa cross-section'alview on an enlarged scale taken along the lines 2-2 of Figure 1.

Figure 3 is a side elevationalview in section illustrating the nozzle and screen assembly shown in Figure 2. v

Figure 4 is a view like Figure 3, but showing another embodiment.

The centrifuge-illustrated in the drawing consists of a rotor 10 carried by the vertical shaft 11. The housing 12 encloses the rotor and is provided with means for collecting the underflow and overflow material, as will be presently explained. The upper and lower main sections 10a and 10b of the rotor are secured together by suitable means such as the clamping ring 13. The outer peripheral portion-14 of the rotor carries a plurality of underflow discharge nozzles 16. The number of nozzles may vary in different instances, depending upon such factors as the size of the machine, the capacity of operation, and the type'of material upon which separation is being made.

' Underfiow material discharging from the nozzles 16 is collected in the housing volute 17. This volute is connected with external piping whereby a large amount of the underflow material is'continuously returned back into the lower impeller portion 18 of the rotor, through the upwardly directed control valve 19. Such an arrangement is disclosed for example in Patent 2,616,620. The

impeller portion 18 of the rotor serves to deliver the underflow material outwardly through the passages 20,

and through the annular orifice 21 into the separating from regions 27, which are located outwardly with respect to the main separating chamber In the embodiment illustrated in Figure 2, the regions 27 are hopper shaped,

and are separated and contoured by the so-called hopper;

blocks 28. These hopper blocks can be made of suitable material, such as fabric reinforced molded palstic, and are each held in place by a suitable means such as a screw 29. The annular rotor space 31, which accommodates the block 28, and which provides the hopper shaped regions 27 between the'blocks, may be formed as an outward extension from the main centrifuge chamber.-

Referring to Figure 3, each of the nozzles 16 carries a screen 32, whereby underflow material must pass through the screen before passing through the nozzle orifice. The nozzle in this instance incorporates features disclosed and claimed in' Patent 2,695,748. Thus the nozzle includes a body '33 which is annular in section (e.g. cylindrical) and is dimensioned to fit within the bore 34 formed in the peripheral wall of the rotor. Suitable sealing means such as the resilient O-ring 36, forms a seal between the body and the rotor. A lug 37 on the body is adapted to interlock with a corresponding recess provided in the rotor wall, whereby when the body is rotated j material.

The screen 32 is attached to the inner end of the body 33. It consists in this instance of a cylinder 43 formed of metal or some other suitable rigid material having sufiicient strength, and provided with a plurality of longitudinally extending slots 44.

is securely attached to the inner end of the body 33, as by brazing or welding.

Assuming that all of-the. nozzlesare constructed as described above, it will be apparent that the underflow material must pass through the screens before being discharged through the nozzle orifices. The width of the slots 44 is such as to prevent oversized material from reaching the nozzles 39. In other words the width of the slots is less than the orifice diameter, thus preventing the nozzles from receiving material which causes clogging.

- After anextended period of operation suflicient solid material may have accumulated upon the screens to reduce the capacity of the machine. When this occurs the machine can heshut down for a suflicient period of. time to permit one to remove the nozzles, andto clean the screens of accumulated solids. Cleaning is facilitated by removing the closure 46.

As will be evident from Figure 2, the screens do not extend into the main centrifuge chamber 22. Therefore they are immersed only in material of underflow consistency maintained within the hopper-like regions 27 by virtue of centrifugal separation and the continuous return of underliow material. Thus the screens do not interfere with proper separating action, and they do not cause any bypassing of material from the main separating chamber through the underflow nozzles.

As shown in Figure 4, the cylindrical screen 48. can be provided; with a plurality ofholes or perforations, instead of the slots 44. Also this screen is provided with a permanent end closure 49, and it is removably seated upon the collar 51 provided on the body 33. Suitable attaching means, such as the pin 52 and the L-shaped slot 53, facilitate attachment and removal of the screen.

in connection with this embodiment it will be noted that the end closure 49 is conical shaped. This facilitates the deflection of fluid material to which the end of the screen may be subjected, and tends to minimize accumulation of solids. upon the end surface during operation.

I claim:

1. In a centrifuge of the continuous type, a rotor having means for supplying a feed material to the separating chamber of the same and means for discharging a centrifugally separated overflow, the rotor also having a main separating chamber adapted to receivethe feed material, a plurality of underflow nozzle assemblies removably seated in circumferentially spaced bores in the peripheral annular wall of the rotor, each nozzle assembly including a hollow body having only its outer portion seated in one of said bores for ready removal of the assembly from the rotor, the inner portions of said nozzle bodies being free from support by the rotor and being located in regions within the rotor generally surrounding the main separating chamber and which contain only material of underflow discharge consistency, and a screen carried by the inner portion of each body through which underflow material is caused to flow in discharging from said regions through said nozzle assemblies, said screens being diS- posed entirely within said regions. and formed for direct flow of underflow material therethrough.

'The inner end is provided with a removable closure- E6. The slotted cylinder 43 I 2. A centrifuge as in claim 1 together with means within the rotor forming regions that are hopper-like, and in which thescreens of said nozzle assemblies aredisposed completely within such hopper-like regions.

3. In a centrifuge of the continuous type, a rotor having means for supplying a feed material to the separating chamber of the same and also means for discharging centrifugally separated overflow and underflow fractions, a plurality of underflow discharge nozzle assemblies, each assembly comprising a hollow elongated body, circumf'erentially spaced bores formed in an annular peripheral wall of the rotor adapted to accommodate said nozzle bodies, means for releasably locking only the outer end portion of each of said nozzle bodies to said annular wall with the inner portions of the body face of separate support, a plurality of screens mounted upon the inner portions of the nozzle bodies, the interior of the rotor being formed to provide a main separating chamber receiving feed material and hopper-like underflow receiving regions extending outwardly from the main separating chamber to said bores and generally embracing the separating chamber, the material maintained within said regions being of underflow discharge consistency, said screens being disposed completely within said regions and formed for direct flow of underflow material therethrough,said locking means whenreleased permitting ready removal of the nozzle assemblies from the rotor and means for continuously returning underfiow material back into the outer part of the main separating chamber.

4. An underflo-w nozzle construction for a centrifuge of the continuous type wherein a feed material is supplied continuously to the separating chamber of a rotor for centrifugal separation and in which the rotor has provision for continuous discharge of overflow and underflow fractions, the underfiow fraction being continuously discharged from a zone of substantial depth of underfiow material 'of discharge. consistency maintained in the outer peripheral portion of the rotor chamber, there being circumferentially spaced openings in the rotor adapted to receive underflow discharge nozzles; said underflow nozzle construction comprising a body forming a flow passage for underflo w discharge material, the body having a discharge nozzle at its outer end and a screen carried by the inner portion of the body, the outer end portion only of the body being attached to the outer peripheral wall of the rotor for ready removal therefrom, the inner portion of the body being free from supports, said screen forming means to pass underflow discharge material entering said passage from the interior of the rotor without substantial change in the direction of flow and to prevent delivery of oversize fragments to the nozzle, said screenbeing disposed completely within said zone of discharge consistency.

References Cited in the file of this patent UNITED. STATES PATENTS 

